According to the design of a means for being electrically connected to a piezo-electric plate, the prevent inventor has disclosed in R.O.C. (Taiwan) Patent Publication No. 527067, R.O.C. (Taiwan) Patent No. M252149 and R.O.C. (Taiwan) Patent Publication No. 535999. In conventional technology, electrodes of the piezo-electric plate are individually electrically connected to power electrodes of a circuit board by a welding manner of electrically connecting line material, a pressing and connecting manner of electrically conductive and elastic sheet or other means for being electrically connected to the electrode so as to form a circuit. In order to eliminate the vibrational energy of the piezo-electric plate, an elastic element is disposed between the piezo-electric plate and the circuit board for absorbing the vibrational energy of the piezo-electric plate. According to the above-mentioned design, the means for being electrically connected to the electrode and the elastic element are disposed on the piezo-electric plate, and the direction of the means is perpendicular to that of the elastic element (i.e. the means for electrically connecting electrode is located bedside the piezo-electric plate, and the elastic element is located under the piezo-electric plate). Although the above-mentioned patent disclose a preferable constraining force capable of preventing the piezo-electric plate from escaping because of vibration the electrode must be welded in the manufacturing process so as to be effectively mounted. Thus, the manufacturing process is still complex. Furthermore, although R.O.C. (Taiwan) Patent Publication No. 527063 discloses that a means for being electrically connected to an electrode and an elastic element are firstly joined and disposed on a side of a receiving box and a piezo-electric plate is then disposed thereon, the elastic element only absorbs a little vibrational energy of the piezo-electric plate because the piezo-electric plate is in the vibrational state. Thus, if the piezo-electric plate of conventional technology is in the high vibrational state, it is easy to generate noise because the piezo-electric plate collides with the receiving box.